Bump Shouldly from 4.1.0 to 4.2.1 in /src (#490)

Bumps [Shouldly](https://github.com/shouldly/shouldly) from 4.1.0 to 4.2.1.
- [Release notes](https://github.com/shouldly/shouldly/releases)
- [Changelog](https://github.com/shouldly/shouldly/blob/master/BREAKING%20CHANGES.txt)
- [Commits](shouldly/shouldly@4.1.0...4.2.1)

---
updated-dependencies:
- dependency-name: Shouldly
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

src/Cake.Issues.Reporting.Generic.Tests/Cake.Issues.Reporting.Generic.Tests.csproj

@@ -36,7 +36,7 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="Shouldly" Version="4.1.0" />
+    <PackageReference Include="Shouldly" Version="4.2.1" />
     <PackageReference Include="StyleCop.Analyzers">
       <Version>1.1.118</Version>
     </PackageReference>